Smoke density and color indicating means



April 2, 1968 H. E. KRAUS ETAL SMOKE DENSITY AND COLOR INDICATING MEANS 2 Sheets-Sheet 1 Filed Oct. 12, 1965 Pro E. Krdus Wa/fer A. 5m ill;

ATTORNEYS A ril 2, 1968 H. E. KRAUS ETAL 3,376,425

SMOKE DENSITY AND COLOR INDICATING MEANS 2 Sheets-Sheet 2:

Filed Oct. 12, 1965 l. II

INVENTORS I HowardE Kraus Walter A. Smith d ra m x w H. a

lll

BYWXWM ATTORNEY United States Patent Oh 31 ,376,425 Patented Apr. 2, 1968 ice 3,376,425 SMOKE DENSITY AND COLOR INDICATENG MEANS Howard E. Kraus, Erie, Pa and Walter A. Smith, East Orange, N.J., assignors to Robert H. Wager Co., Inc., South Orange, N.J., a corporation of New Jersey Filed Oct. 12, 1965, Ser. No. 495,170 13 Claims. (Cl. 250-218) ABSTRACT OF THE DISCLOSURE This invention relates generally to improved smoke indicating apparatus, and more particularly to apparatus for indicating the density and color of smoke in a duct or other conduit.

As exemplified by the prior US. Patents Nos. 2,118,716 and 2,291,776 in the name of Robert H. Wager, various smoke indicating systems have been proposed in the patented prior art including means for visually observing the density and color of smoke in a stack. As is known in the art, black smoke results from incomplete combustion of fuel (supplied to the burner of a boiler or other combustion device), and white smoke results from an excessive quantity of air. Many systems have been proposed for monitoring the smoke density and/or color so that the air-to-fuel ratio of the boiler may be controlled to effect maximum combustion efiiciency.

The primary object of the present invention is to provide an improved smoke density and color indicating apparatus that is of simple, durable construction, temperature compensated, efiicient and reliable in operation, and is relatively inexpensive to manufacture, install, serv ice and repair. The invention is characterized by the provision of a light source for directing light across the smoke conduit, in combination with smoke density indicating means responsive to the intensity of the light transmitted through the smoke, and smoke color indicating means responsive to the intensity of the light reflected by the smoke when the color thereof is white.

In accordance with a more specific object of the invention, the smoke density indicating means includes a plurality of successively operable first pilot light means for indicating at a glance the various levels of the density of the smoke. These first pilot light means include a SMOKE pilot light that is energized only when the density of the smoke is above a predetermined level.

According to another feature of the invention, a pair of smoke color indicating pilot lights are provided that are alternately operable only when the aforementioned SMOKE pilot light is energized (i.e., only when the smoke density exceeds a predetermined value). This pair of smoke color indicating pilot lights comprises a normally energized BLACK pilot light, and a normally de-energized WHITE pilot light. Means responsive to the intensity of the light reflected by the smoke are provided for de-energizing the BLACK light and for energizing the WHITE light when the intensity of the reflected light exceeds a predetermined value.

Another object of the invention is to provide meter means for indicating directly the density of the smoke. These meter means include relay means for successively energizing and de-energizing the smoke density pilot light means. In accordance with a further object of the invention, improved meter calibrating means are provided for ellecting full scale meter deflection for various numbers of Ringelmann units as desired. Amplifier means provided with external zero and gain adjustment means amplify an electrical signal that is generated by photocell means in accordance with the intensity of the light transmitted through the smoke, said amplifier means being of the inverse type so that the meter reading varies inversely relative to the intensity of the transmitted light. Consequently, to calibrate the meter for a desired Ringelmann unit full scale range, the stack is cleared of smoke and the meter is first zeroed by appropriate variation of the amplifier zero adjustment means. Means are then operated to reduce the intensity of the light by a predetermined amount (for example, twenty percent), whereupon the gain control is adjusted to effect a desired meter reading (for example, 50% when a two Ringelmann unit full scale range is desired). The intensity of the light is then returned to its normal level, whereupon the system is operable to provide full scale for the desired number of Ringelmann units.

Still another object of the invention is to provide smoke indicating apparatus including main and remote panels each including smoke density indicating means consisting of a meter and a plurality of successively operated pilot lights, and smoke color indicating means comprising a pair of pilot lights that are alternately energized only when the smoke density exceeds a given value.

A further object of the invention is to provide smoke indicating apparatus of the type described above that is automatically temperature compensated without the requirement of reference photocell means or the like. In accordance with the invention, the photocell means that receive the transmitted light are of the silicon solar cell type having at low loads a flat temperature coeflicient. These photocell means are connected with high impedance smoke density amplifier means via preliminary amplifier means having a low input impedance, whereby the desired temperature compensation is automatically achieved.

Other objects and advantages of the invention will become apparent from a study of the following specification when considered in conjunction with the accompanying drawing, in which:

FIGURE 1 is a partially sectioned detailed side elevational view illustrating the physical arrangement of the components of the smoke indicating means relative to a smoke conduit;

FIGURE 2 is a schematic electrical diagram of the smoke indicating apparatus;

FIGURES 3 and 4 are front views of the main and remote panels, respectively; and

FIGURE 5 is a detailed schematic electrical diagram of one of the pilot light means.

Referring first to FIGURE 1, the smoke indicating apparatus is connected with the flue or smoke stack conduit 2 through which smoke and combustion gases from the boiler 4 pass upwardly to atmosphere. Mounted in one wall of the smoke conduit 4 is a light source housing 6 containing a light bulb 8 for directing rays of light 10 directly across the conduit 4. The housing 6 includes a metal pipe 12 (of steel or aluminum for example) that is secured in a corresponding opening contained in the flue wall.

Mounted on the fiue 2 directly across from the light source housing 6 is a smoke density housing 14 having a pipe 16 that is secured in a corresponding opening in the flue wall. As disclosed in the aforementioned Wager patents, the housing 14 contains an angularly arranged mirror 18 that so reflects the light rays to mirror 19 as to permit visual inspection of the smoke in the conduit at the remote inspection station 20. The central portion of the mirror 18 contains a transparent horizontal slit (not shown) behind which are mounted smoke density photocell means 22. A portion of the transmitted light passes through the slit and impinges upon the photocell means 22, thereby generating a first electrical signal that is a function of the intensity of the incident light.

Mounted on the flue 2 adjacent, and on the same side as, the light source 8 is a smoke color housing 23 having a metal pipe 24 secured in a corresponding opening in the flue 2. Mounted on a plate within the housing 23 are the smoke color silicon photocell means 26 that are arranged to receive light from source 8 that is reflected by the white smoke in flue 2. The housings 6, 14 and 23 include conventional lenses that are cleaned by fluid supplied via conduits 28. Electrical conductors 30 electrically connect the components of the housing as will now be described.

Referring now to FIGURE 2, the bulb 8 (which comprises, for example, a 100 watt, rough service, inside frosted bulb) is energized from a 115 volt alternatingcurrent voltage source 36 via on-ofl? switch 37, voltage regulator 38 and conductor means 40. Connected in series with the bulb 8 is a factory pre-set variable resistor 42. Normally-closed push button test switch 43 is connected in parallel across the variable resistor 42.

The smoke density photocell means 22 of FIGURE 1 comprises a plurality of parallel-connected silicon photocells 22a that generate a first electrical signal that is applied, via low input impedance preliminary amplifier 44, to the input terminals of a conventional, inverse-type smoke density magnetic amplifier 45 having external zeroing and gain adjustment means including variable resistors 46 and 48, respectively. The output terminals of the smoke density amplifier 45 are connected with a relay meter 50 via an output network including identical parallel-connected resistors 52, 54, 56, 58 and 59, and instrument protection means comprising Zener diode 60 and capacitors 62 and 64. More specifically, the input terminals of relay meter 50 are connected in seires in the parallel branch including resistor 59.

The white smoke photocell means comprise a plurality of parallel-connected photocells 2611 that generate a second electrical signal that is a function of the intensity of the light 66 reflected by white smoke in the conduit 2. This second signal is applied to the input terminals of a two-stage magnetic amplifier 70. Connected between the stages of this amplifier are sensitivity adjustment means including a variable resistor 72. The output stage of the white smoke amplifier 70 operates relay means including a solenoid 74 that is energizable to displace movable relay contact 76 out of engagement with stationary contact 78 and into engagement with stationary contact 80.

Referring now to FIGURE 3, it will be seen that the main panel 82 has a face plate containing the relay meter 50, the screw means 46a and 48a for adjusting the zero and gain adjustment means 46 and 48, respectively of first magnetic amplifier 45, the on-oif switch 37 and the push-button test switch 43. The main panel also includes five pilot lights 84, 85, 86, 87, 88, respectively, bearing the legends CLEAR, NORMAL, SMOKE, WHITE and BIJACK. The meter 50 includes a conventional pointer 90 that is pivoted across a scale that indicates smoke density as a percentage (O-100%). As is known in the art, the relay meter includes a pair of control means 92 and 94 that are settable to selected positions on the scale for operation by pointer 90 to operate the movable relay contacts 96 and 98 shown in FIGURE 2. Consequently, when pointer 90 pivots past control means 92, movable contact 96 is displaced from stationary contact 100 to stationary contact 102. Similarly when pointer 90 pivots past control means 94, movable relay contact 93 is dis- Referring again to FIGURE 2, movable contact 96 is connected to one side of a low voltage source of alternating current 97, the other side of said source being connected with one terminal of each of the pilot light indicator means 84-88, respectively. Stationary contacts 100, 104, 106, and 78 are connected with the other terminals of indicator means 8488, respectively, and stationary contact 106 is also connected with movable contact 76 via junction 112 and conductor 110.

If desired, remote panel indicating apparatus may be provided including a remote panel 120 (FIGURE 4) containing a conventional remote meter I122 and five pilot lights 123, 124, 125, 126, 127 labelled CLEAR, NOR- MAL, SMOKE, WHITE and BLACK, respectively. As shown in FIGURE 2, the pilot lights 123-127 are connected in parallel with pilot lights 84-88, respectively. Remote meter 122 is connected in series with the parallel branch including resistor 56 of the output network of control amplifier 44, and continuously presents the same reading as meter 50.

Operation Assume that all relay and switch contacts are in the positions shown in FIGUREZ, that resistor 42 has been factory preset to cause a twenty percent reduction in the intensity of the light produced by source 8 when test switch 43 is opened, and that no smoke is initially present in the smoke conduit 2. Since all the light is transmitted from bulb 8 to photocells 22a, the pointer 90 of relay meter 50 is adjacent zero (owing to the inverse relationship between light intensity and output current achieved by the control amplifier 45). Zeroing adjustment 46 is varied on main panel 82 to cause pointer 90 to be directly opposite the zero reading on the scale.

To calibrate the apparatus for military marine use (wherein 100% meter reading is desired for a full scale range of two Ringlemann units) push button test switch 43 is opened to reduce by 20% the intensity of the light source, whereupon gain control 48 is varied to cause pointer 90 to be opposite the 50% reading on the scale of relay meter 50. Push button switch 43 is closed and the meter pointer 90 is again zeroed by zero adjustment means 46. The above calibration procedure may be repeated until the desired accuracy of readings is obtained.

It is obvious that to obtain meter ranges of three, four and five Ringelmann units, the gain control 48 is .adjusted (with test switch 43 open) so that the pointer 90 is at positions opposite the readings 33% 25% and 20%, respectively. Other meter ranges may be achieved by appropriate settings of the gain control adjustment 48.

Since the. stack is now clear of smoke and the maximum quantity of light is received by photocell means 90 of relay meter 50 reaches control member 92 (which i has been set, for example, at 33 /s%), movable contact 96 is disengaged from contact .100 and engaged with coni tact 102, whereupon CLEAR lights 84 and 123 are de-energized and NORMAL lights and 124 are energized (via contacts 96, 102, 98 and 104). As the density of the black smoke in flue 2 increases, the meter readings increase until the pointer passes the second control member 94 (which has been set, for example, at 66% At this time, movable contact 98 is disengaged from contact 104 and engaged with contact 106, whereby the NORMAL lights are de-energized and the SMOKE lights 85 and 125 are energized (via contacts 96, 102, 98 and 106). Furthermore, owing to the supply of current to contact 76 via junction 112 and conductor 1'10, BLACK lights 88 and 127 are energized via contacts 76 and 78. The same meter readings are presented on meters 50 and 122, and the corresponding pilot lights on the panels are operated simultaneously.

Assume now that the supply of oxygen is increased relative to the quantity of fuel being burned, whereupon the color of the smoke passing through the conduit changes from black to white. Since the density of the smoke has not changed (i.e., since only an extremely small quantity of light reaches the photocell means 22), the reading on meters 50 and 122 is quite high (on the order of 100%) and SMOKE lights 86 and 125 remain energized. However, owing to the quantity of light 66 that is reflected by the white smoke to the photocells 26a, the magnitude of the output signal from the two-stage relay amplifier 13 increases until the tripping voltage of solenoid 74 is reached, whereupon contact 76 is disengaged from contact 78 and engaged with contact 80, with the result that BLACK lights 88 and 127 are de-energized and WHITE lights 87 and 126 are energized.

In the event that incomplete combustion and accompanying return to the back smoke condition should occur, the light reflected to photocell means 26a is reduced, whereupon relay contact 76 is returned to its illustrated position to energize BLACK lights 88 and 127 and to de-energize WHITE lights 87 and 126.

In the event that the density of the smoke is progressively decreased, the light transmitted to photocells 22a is progressively increased, and the meter readings are progressively decreased. When pointer 90 passes control member 94, relay contact 98 is returned to its illustrated position to de-energize lights 86, 88, .125 and 127, and to energize lights 85 and 124. Upon further decrease in smoke density, relay contact 96 is returned to the illustrated position whereupon NORMAL lights 85 and 124 are de-energized and CLEAR lights 84 and 123 are energized.

Referring to the simplified schematic diagram of FIG- URE 5, each of the pilot light means I of FIGURE 2 consists of a pair of parallel-connected miniature flanged base lamps L connected with the low voltage source via one or more of the aforementioned relay switches S. Test switch means T and associated circuitry are provided for testing the operability of lamps L when the relay switch S is open.

As indicated above, the photocells of the density and white smoke indicating means are preferably silicon solar cells of the self-generating type, whereby the undesirable aging factor associated with other types of cells is avoided. In accordance with an important feature of the invention, at least the cells 22a that receive the transmitted light are of the type having a flat temperatur ecoefiicient when operaed with a short circuit load or a load resistance less than about 100 ohms. An example of such a cell is the silicon solar cell Model 1020'E6 manufactured by the International Rectifier Company. Since the control amplifier 45 normally has an input load impedance of on the order of 2000 ohms, to provide automatic temperature compensation for the apparatus described above, the prelimiinary amplifier 44 (having the proper characteristics and an input impedance on the order of 100 ohms) is connected between the photocell means 22 and the magnetic amplifier 45. In this manner, the photocells 22a are so loaded that owing to their inherent temperature characteristics, they automatically afford the desired temperature compensation.

The voltage regulator, which regulates the voltage of the magnetic amplifiers and the light bulb, is a conventional Sola regulator. While because of their dependability and reliability, conventional magnetic amplifiers have been selected for amplifying the density and white smoke indicating signals, it is apparent that other types of amplifier means could be used equally as well. The meters are conventional and normally are of the l milliampere, directcurrent taut band type. Although the smoke indicator apparatus is particularly adapted for marine boiler smoke monitoring use, it is apparent that the invention may be utilized for many other types of similar non-marine applications, such asmonitoring the color of the gases of combustion in compression ignition engines, waste disposal furnaces, and the like.

While in accordance with the provisions of the patent statutes, the best form and embodiment of the invention has been illustrated and described, it will be apparent to those skilled in the art that additional changes and modifications may be made in the apparatus described without deviating from the invention set forth in the following claims.

What is claimed is:

1. Apparatus for indicating the density and color of smoke flowing through a conduit, comprising light source means arranged on one side of said conduit to direct a light beam transversely across the conduit; normally de-energized first (86), second (88) and third (87) indicating means;

smoke density responsive means mounted on the opposite side of said conduit from said light source and operable when the quantity of light transmittedacross the conduit is reduced below a first given value for energizing said first indicating means and a single one of said second and third indicating means;

and smoke color responsive means mounted on the same side of said conduit as said light source and operable when the quantity of light reflected by the smoke exceeds a given value for reversing the states of energization of said second and third indicating means.

2. Apparatus as defined in claim 1 wherein said smoke density indicating means comprises first photocell means for generating a first electrical signal that is a function of the intensity of the transmitted light, first inverse amplifier means for amplifying and inverting said first signal, and first meter means for indicating the magnitude of said inverted first signal.

3. Apparatus as defined in claim 2, and further includmg normally energized fourth (84) and normally de-energized fifth indicator means, said smoke density responsive means, including also means (96) operable when the quantity of the light transmitted across the conduit is initially reduced to a second given value for reversing the states of energization of said fourth and fifth indicator means.

4. Apparatus as defined in claim 3 wherein said smoke color indicating means comprises second photocell means arranged to generate a second electrical signal that is a direct function of the intensity of the light reflected by the smoke, and second amplifier means for amplifying said second electrical signal.

5. Apparatus as defined in claim 4, wherein said means for reversing the states of energization of said second and third indicating means, respectively, comprises relay means operable by said second amplifier means when the amplified second signal exceeds a predetermined value.

6. Apparatus as defined in claim 3, wherein each of said indicating means comprises pilot light means.

7. Apparatus as defined in claim 2, wherein said first amplifier means includes zero adjustment means and gain control adjustment means.

8. Apparatus as defined in claim 7, and further including means for reducing the intensity of the light produced by said light source a predetermined amount, said light intensity reducing means, said zero adjustment means and said gain adjustment means being operable to calibrate the range of response of said first meter means when no smoke is present in said conduit.

9. Apparatus as defined in claim 8 wherein said light source means comprises a bulb, a voltage source, resistance means, and circuit means connecting said bulb and said resistance means in series with said source, and further wherein said light intensity reducing means comprises a normally-closed switch connected in parallel with said resistance means.

10. Apparatus as defined in claim 9, and further including voltage regulator means for maintaining constant the voltage of said source.

11. Apparatus asidefined in claim 4 wherein said second amplifier means comprises a two-stage amplifier, and further including sensitivity adjustment means connected between the stages of said second amplifier means for controlling the sensitivity of said second amplifier means.

12. Apparatus as defined in claim 6, and further including main panel means containing said first, second, third,

fourth and fifth indicator means and said first meter means. I

13. Apparatus as defined in claim 12, and further including additional sixth, seventh, eighth, ninth and tenth indicator means connected in parallel with said first, second, third, fourth and fifth indicator means, respectively,

second meter means for measuring the magnitude of the.

amplified signal of said first amplifier means, and remote panel means containing said second meter means and said sixth, seventh, eighth, ninth and tenth indicator means.

References Cited UNITED STATES PATENTS 8/1942 Wager 88l4 Cahusac et al 250-218 

